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Why is Coke & orange juice rusting a nail relevant to real life situations?

Why would the information on which liquid out of Coke or orange juice will rust the nail most... be important or be relevant to real life situations?

Jessica M. [last name deleted for privacy by Editor]
student - Miami, Florida
2004

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Hi, Jessica. It's a bit hard to say. In the old days students used more "scientific" reagents like acids and alkalies of specific normalities, so you could more straightforwardly learn chemistry (3 parts of this acid neutralized 2 parts of that alkali, etc.), and take that chemistry learning directly out into the world with you for engineering and science careers, anti-corrosion design, etc. But these days they don't let you use "real" chemicals in school anymore; you are restricted to using safe food-quality materials like Coke and orange juice. But hopefully you can still learn some of "the scientific method" from your experiment, i.e., how to structure and run a project in order to derive scientific facts from it, how to keep a lab book, and the difference between a hypothesis and a fact, an assumption and a proof, an observation and a conclusion. Good luck!

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

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P.S. With the benefit of the very good insights offered by other responders in this thread, I realized that my original opening comment was hasty and negative, so I revised it to what you now see.

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2004

That's one of the best questions I've seen from a student in this forum, Jessica. The study of corrosion is extremely important, and its kept people like me employed for a lot of years. Jessica, everything we do on a daily basis has somehow been effected by the study of corrosion, from the car you get in to go to school,to the internal computer parts that are on the system you used to type your question to this forum, to the water you drink, to the school building itself..all these things have to be protected from corrosion. Our cities infrastructures are crumbling from corrosion, and will cost billions/trillions of $$$ to fix.

Perhaps if one student's interest in this science is sparked, by doing some of these 101 experiments, that student may indeed come up with the next new "holy grail" of coatings that will last indefinitely. Or, at the very least, perhaps that person may want to pursue a career in the metal finishing industry (we need the help!) These experiments seem boring, I know, Jessica, but the basic science behind it is very important. Personally, I'd rather be learning about nails corroding in soda pop, as opposed to memorizing the order in which our past presidents have been elected.

Marc Green
anodizer - Boise, Idaho

Jessica,

To answer the question you posed: I can't think of any reason it would be either important or relevant as stated. If it tweaks your interest enough, follow up with some 'real' chemicals and metals with defined characteristics. If not, consider it a ritual that your school requires to get a passing grade. Just remember in later life that there was something going on there; even if you don't know what it was!

PS. Congratulations on being able to think such thoughts, and being able to express them in public.

Tom Gallant
- Long Beach, California
2004

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I'm just guessing here, but I was under the impression that this was a grade school experiment. Unfortunately, in this forum, all we see is the questions on the beginning of an experiment, not what happens in the end, and we have no idea what kind of follow up the teachers do to explain why certain things rust faster than others in a given solution. But judging by the amount of questions we see on nails, and pennies, it does seem that these experiments are not fully explained, as to their purpose. It would be neat to see a teachers response (in this forum) to Jessica's question.

Marc Green
anodizer - Boise, Idaho
2004

I would like to know how to grade rusting process. for example, 1+ for a little rust, 2+ for a lot of rust and so on.

Adnan S.
science project - Jacksonville, Florida
2004

I am doing a science project on "do nails rust faster in dark soda or light soda?" my teacher told me to look up rust and iron oxide and how it is formed, but I cannot find anything on it. I mean I understand what it is but I cannot find out how it is formed so if you could help.

Anne b.
school - Portage, Indiana, United States
2004

The colors in colas and soda are mostly inert, the corrosive action is caused by carbonic acid (of which there is a very small amount in soft drinks), there is also citric acid , but that amount is negligible most of the time. As for your teacher wanting to know the difference, why doesn't she ask something more complicated? Perhaps WHY carbonated drinks are corrosive rather than which one dissolves things quicker?

I never liked chemistry class myself, specifically for questions like these. They make the students learn nothing, and are ultimately about nothing. Sorry I'm a bit bitter. http://science.howstuffworks.com/question445.htm

Good quick explanation of iron oxide.

Marc Banks
- Elizabeth City, North Carolina
2004

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I hope this isn't too far out into left field, But the first thing that I thought of when I read the question is that when I was a kid my mother always told me that if coke will corrode a nail or clean a penny, think about what it will do to your teeth and stomach (as a deterrent for drinking so much pop). But I mentioned it to my science teacher one day and she said that pennies and nails were not made of the same material as your teeth and stomach so why would it have the same effect? Rack it up as an old wives tale and end of story until last year when my 9 year old came home from school and wanted to put a penny in a glass of coke over night to see how clean it would make it! I just told him to drink his coke and forget about it. Sorry for the lame entry into the penny in the coke experiment. Sheldon Taylor supply chain electronics Wake Forest, North Carolina 2005

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2005

This is becoming an interesting thread. I must agree with Marc on his comments and would like to add that if more people had paid attention to High School chemistry, we would not be seeing so many people asking how to repair things they have damaged by using inappropriate (but commercially available) cleaning chemicals. For some reason people appear to regard all chemicals as dangerous and useful things (such as salt) as non-chemical. Unfortunately, everything is made from chemicals or elements: the food we eat, the clothes we wear etc etc. Even salt is a chemical (sodium chloride). Cooking an egg is even a polymerisation reaction; boiling a kettle of water is showing that gases are less soluble in hot water than cold - a very important scientific fact that has (in part) allowed life as we know it to evolve on Earth.

Unfortunately everything we do is ruled by scientific principles and we cannot get around this fundamental fact, so it is essential that we understand the "forces" that govern us. This is also true for our health; I accept that the effects of cola on teeth will be different to its effect on copper coins, but all the same, cola is a very acidic solution (do a pH test on it if you don't believe it) and this will have an adverse affect on the structure of our teeth. Furthermore, the sugars in these soft drinks will cause dental decay that will cause toothache and even result in the loss of teeth.

Science must be taught in a way that students can relate to. If it is not, it will be an automatic turn-off. Whilst safety has possibly become over-done with regard to science lessons, the basic principles still need to put over in a sensible and safe way. The use of household materials is one such way of doing so without overburdening the student with meaningless technical terms and exposing them to unnecessary hazards. Once the basics have been grasped, then the students should be encouraged to use scientific practice, terminology and thinking processes to work their way through life. In this way they will become better and more understanding citizens as they will understand how their actions will impact on the lives of others.

The bottom line is that SCIENCE IS FUN.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

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Despite of all the posted answers I believe this is a good question. Coke and orange juice contain a variety of ingredients harmful to people and nails. The phosphoric acid in coke and the fruit acid in orange juice will start the corrosion process and the water (actually the Hydrogen of the water) in both will nurture it. The relevance to real life is: DO NOT DRINK COKE! Drink orange juice in/with moderation! Acids in both drinks are creating an imbalance in our bodies when used unwisely. Furthermore the phosphoric acid in coke will damage teeth or braces when used in abundance and long term. Rolf Reiser - Boulder, Colorado 2005 2005 "The relevance to real life is: DO NOT DRINK COKE! Drink orange juice in/with moderation! " But if Jessica finds that the orange juice proves more corrosive than the Coke, Rolf, what is the real-life lesson then? Does it then become: "DO NOT DRINK ORANGE JUICE! Drink Coke in/with moderation"?  :-) Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey 2005 OK, here's a point, I ignored the "do not drink coke" advice and I have never had a cavity, and I still have all of my teeth. (I'm 44) So where in the seemingly logical argument about the amount of acids or corrosives in drinkable liquids will I fit in? What about people that have had very little to do with acidic drinks that have severe problems with tooth decay? I believe that our responsibility as adults (not just the teachers) is to spark interest, especially in children, to explore and to think. So if every generation of teacher since coke was invented asked his/her student to throw a penny or nail into a glass of it and see what the results are, I guess that's ok. I know it's already been expressed, but in this case the reaction to the question is more important than the answer to the question. Sheldon Taylor supply chain electronics Wake Forest, North Carolina The "do not drink coke" advise is for Children and not for Adults. Because children don't know when to stop. Some teeth are genetically prone to battle coke etc. not all teeth are and so we play safe with children. 44 is not old enough. You could drink lots of coke and see what happens to your teeth at age 60 Sonali Kokane - Mumbai, Maharashtra, India 2005 2005 There is certainly nothing wrong with the advice that children avoid Coke, and Trevor's posting is good in explaining why. But what is wrong is teaching children to twist the interpretations of their experiments to 'prove' the points that we want to make, such as: "coke corrodes nails, therefore it causes tooth decay and is bad for you". This is the classic definition of 'junk science' -- decide what political point you want an experiment to prove, and keep manipulating it and reinterpreting it as wackily as necessary until the "results" can be stretched to prove the point :-) Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey

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2005

Is there any legit way to get back to Jessica's original query? LOL. Her teacher is trying to get her to use her head and do some experimentation to get a science grade. Just go with the flow Jessica, just go with the flow. oh yah, tell the teacher what he/she wants to hear, you get a better grade that way. ;-)

When I'm 60 I'll let everyone know if I still have all of my teeth.(It's too bad she's not doing experiments with wind erosion, because I think wind is eroding my hairline, or gravity, because I KNOW gravity is effecting my waist size) Now we're talking real life application!

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina

Where is the question of getting back to Jessica's question? her question was answered at the very beginning. Our responses reflect the philosophical aspect of her question. These responses will help shape her thoughts, the next time Jessica reaches out for a can of coke. The real-life application of gravity is the fact that we are able to stand on the ground and not quite dangling in the space. A high school student can go further and study how gravity affects tides and a graduate student would find it fascinating that using the law of gravity he can calculate the radii of the planets by just sitting in his drawing room. How gravity affects one's waistline will follow eventually. Likewise for wind and coke. But every student has to find a way to get over such idiosyncrasies as every education system is plagued by one or another. So the best thing for Jessica is to give what her teacher wants in order to get the grades. In Mumbai emphasis is given on learning by rote and college education gives more emphasis on applications. Consequently, a Mumbai student does not fare well in fundamentals but makes the most of what he knows of applications.

Sonali Kokane
- Mumbai, India
2005

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2005

Speaking of the philosophical ramifications of her questions... I've always been of the opinion that the only legitimate answer to a students question "What does this (specific idea or thing) have to do with real life?" is almost always NOTHING. But, it's not SUPPOSED TO either - odds are strongly against anyone ever really being in a position where they desperately NEED to be able to do long division, and regardless of the arguments above regarding tooth decay by coke the likelihood of anyone ever being in a position where knowledge regarding the relative corrosion rates of nails treated with unknown coatings when dipped in liquids of unknown compositions is pretty much nil. But, that isn't the point of the exercise, the point is (or at any rate, Should Be) to teach the student to apply the scientific method (or in the case of long division, mathematical logic) to a situation of their own choosing.

The reason why these so called experiments are a waste of everyone's time is that the TEACHERS fail to realize what they should be teaching. The point of the experiment that the children are doing should not be to actually find out what soda will rust a nail faster, the point should be to find out if the student understood how to apply the scientific methods to test a hypothesis.

When the teachers assign a chemistry experiment, and then give so little guidance that the vast majority of the students aren't even aware of what "hypothesis" means, the students are cheated out of a valuable learning opportunity and instead forced to complete a bunch of meaningless busy work - so the only answer to Jessica's original question is that knowledge of what liquid will rust nails fastest is completely useless, but that what she should have learned from the assignment was how to form a hypothesis from a position of limited knowledge and then test it against real world conditions to see if it holds water.

While I agree with Trevor Crichton that students desperately need to learn both scientific fundamentals, there is no way that this assignment is the result of a teacher REALLY WANTING to use better materials and being forced into using Coke instead - almost all "experiment" questions that get posted here that are of this type are from students in 4th through 6th grade, I doubt that any teacher has ever wanted to put real reagents in the hands of kids that aren't even 13 yet. These assignments are meant to show how to use the scientific methods; the students are too young to get any meaningful results other than that it is possible to test an idea. Now, if students in high school were doing these type of projects, it would be another matter entirely - then I would agree wholeheartedly that the teacher is trying to teach fundamentals or something equally useful from the matter and is just using poor materials.

But, given the age group, the problem with the experiments isn't the fact that they use materials that prevent any meaningful conclusions, the problem is that the teachers fail to understand what it is that they should be trying to teach.

But, to steal a line, that's just my opinion - I could be wrong.

Jim Gorsich
Compton, California, USA

Oh My God! This question/answer has sent our heads reeling!

Amit Amembal
- Mumbai, INDIA
2005

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2005

Jessica:

Very good question Jessica. As many of the gents above have stated, theoretically there is no real life relevance to this experiment other than to teach about the acids contained in each drink. I believe the basic idea is to get you interested in science, because though this may be "junk" science, the practices of experimentation are something that must be instilled early and in a manner that will keep you wanting to experiment, to see what happens when you put chemical A with chemical B.

Hopefully, your teacher gave you the background knowledge about Oxidation and Reduction, so you could form a hypothesis BEFORE you carried out the experiment.

Developing an interest in science will carry you in good stead throughout your school career. You've already demonstrated that even at your age you have an analytical mind, since you're not just taking the work at face value and accepting it, you're actually wondering *why*. Hopefully, if you do continue to study science, you'll be shown more exciting reactions!

Unfortunately, in the mean time, you have to accept that this is the norm for your age group. But please, whatever happens, don't stop questioning, don't stop wondering. Too many valuable young minds have been quashed by never asking "Why are we doing this?"

Adnan S:

Try surface area. make a regular grid of cotton on a square cardboard frame and hold it over the rust, see how many squares are full of corrosion and use that to grade it. The grading will then depend on how many squares in your grid there are.

Anne B:

I'm not sure how much detail you need to go into but any chemistry text book worth it's salt would have a basic introduction to the rusting process. You might need to go to one suitable for older students. Failing that try searching for "Oxidation of Iron" rather than "rusting".

Nicola Wilcox
planner for a lock manufacturing company. - Walsall, England

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2005 Now that the devastating effects of Coke have been demonstrated, I'd recommend a similar experiment: the lethality of single malt scotch whiskey to worms. Once the dangerous properties of this treacherous liquid have been made clear to everyone, they should send it all to me. I'll dispose of it in an environmentally responsible manner. Heh, heh. Dave Wichern Consultant - The Bronx, New York First of two simultaneous responses I'm pretty good at turning wine into water.... Trevor Crichton R&D practical scientist Chesham, Bucks, UK 2005 Second of two simultaneous responses 2005 David, I want to thank you for bringing the dangers of malt whiskey to the attention of this forum. I've conducted a lot of research on this substance, and I would like to share my conclusions. The MSDS lists these possible side effects from exposure. 1. Members of the opposite sex appear much more attractive than they really are. 2. Driving after consumption of said substance will land you in the Gray-Bar hotel, and cost you lots of money during the next year. 3. Overexposure may lead to bed spins, nausea, vomiting, and severe headache the following morning. 4. Memory loss 5. Excessive talking about things that you probably shouldn't say anything about. 6. Lost time from work. 7. For some strange reason, this substance may result in you getting on the dance floor, when you have no clue on how to dance. These are just a few of the very many known side effects of this extremely hazardous liquid. I'd personally like to thank you, David, for sacrificing your well being in order to rid the world of this stuff before the EPA was forced to get involved, and spend millions of tax dollars on regulation. You sir, are a true hero. Marc Green anodizer - Boise, Idaho   I love your list, Marc. #1 is a good thing rather than a bad thing, and #7 is okay as well. With proper planning, #2 and #6 are easily avoidable. #3 is only just desserts, and #4 can be a blessing. But that old #5! Boy can that be a killer. Regards, Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey

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2005

Poor old Jessica ,,,

She's going to have to read, I hope, all these e-mails

Look at it from a teacher's perspective ... it's MUCH safer for kids to experiment with Coke, salt water and orange juice than using ACIDS or ALKALINES ... OK?

When I grew up there was no Coke nor orange juice (wartime UK) but I still remember learning to NEVER pour water into an acid ... otherwise we got a swipe with a piece of bunsen burner rubber tubing. Marshall was a very good chemistry master, Taunton, 1943.

Jessica, there's a saying you might like

Others follies teach us not
Nor much their wisdom preaches
But most of sterling worth is what
Our own experience teaches

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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2005

Why is everyone arguing over stupid rust!? Oh, its very important to know about corrosion lalala. But there are people like you guys (as you have pointed out) that work on rust everyday but that doesn't mean everyone else in the world needs to know about it!

Lauren

[last name deleted for privacy by Editor]
- Melbourne, VIC, Australia

Hi, I am in grade 10 and I'm doing a science fair project on how liquids stain teeth and how acids affect the amount of stain. I used eggs as a substitute for teeth and soaked them in liquids such as coke, coffee, or blue gatorade for a week. What I noticed was that the coke had a huge amount of stain compared to the other drinks and I assumed it was because of the phosphoric acid. However, I did not get a chance to test citric acid which is another common acid found in drinks. I would like to know which acids break away enamel more and why. Thanks!

Adam M.
- Chicago, Illinois, U.S.A.
December 5, 2011